Such a rubber teat holder is already known from German Offenlegungsschrift No. 2 007 613, in which the ring lip projects radially inwardly toward the longitudinal axis of the suction sleeve, however, in a direction which is away from the upper end of the suction sleeve. The holding edge is constructed as a cuff, which can be placed over the edge of the opening of a milking cup housing. In the case of such a milking cup there resulted always difficulties in holding the rubber teat holder on the milking cup housing. For this purpose, the upper edge of the milking cup housing had openings therein, in order to use the vacuum which exists during the suction cycle between the rubber teat holder and the milking cup housing to hold the cuff on the milking cup housing. However, such a mounting has not proven advantageous because also during the unloading or massaging act actions of force occurred between the rubber teat holder and the milking cup housing which led to a shifting of these parts against one another and alter the operation of the milking cup as a whole. Also it has been found that this known type of milking cup does not meet the rough requirements existing on a form because relatively much damage of the rubber teat holder occurred during the impact of the milking cup. Finally, as a whole, it was shown that this conventional milking cup demonstrated a repeated falling off from the teat during the unloading cycle.
Swiss Pat. Nos. 429 283 and 454 523 also already described rubber teat holders for milking cups in which the suction sleeve at its upper end ends in a high collar which encloses an enlarging space, and which leaves free an opening for introduction of the teat. An annular flange is cast on in the enlarging part of the suction sleeve, which annular flange forms an annular groove between itself and the outside of the suction sleeve, into which annular groove the upper edge of a milking cup housing can be received. Such a rubber teat holder has the important disadvantage that the upper enlarging space which is enclosed by the high collar is under a vacuum during the milking operation. Through this the part of the teat which lies in this area is stressed such that the teat enlarges beadlike, which can result in permanent damage to the teat. However, in the case of this known rubber teat holder the creation of a vacuum in this upper space is especially necessary in order to permit the milking cup at all to hold onto the teat during the entire milking operation.
Swiss Pat. No. 477 812 already discloses a rubber teat holder in which a suction sleeve is provided which usually does not grip around the teat. The suction sleeve transfers then at its upper end into a beadlike high collar which consists of a more solid material whereby the ring lip which encloses the opening for introduction of the teat is constructed as a lip which is turned inwardly against the suction sleeve, and which lip has on its inside an annular rib. Also in the case of this rubber teat holder the entire upper head portion is under a vacuum during the entire milking operation. Also during the entire milking operation, the turned-in ring lip rests through its rib on the teat and exerts a considerable pressure especially near the root of the teat which is particularly sensitive. This continuous pressure is supposed to imitate the closing movement of the mouth of a calf, however, effects in reality an extensive cutting-off of the milk flow in the teat.
The basic purpose of the present invention is now to produce a rubber teat holder, which permits a good holding of the milk cup without affecting the teat and the milk flow.
This purpose is attained inventively in the case of a rubber teat holder of the above-mentioned type by the ring lip being constructed sloped inwardly toward the suction stub or at a maximum lying in a plane which extends perpendicularly with respect to the longitudinal axis of the suction sleeve and that the inside diameter of the ring lip is less than the inside diameter of the slightly conical part of the suction sleeve, an imaginary extension of the conical taper of the part intersecting the inner edge of the ring lip.
Through this, the advantage is achieved that the ring lip is turned inside against the suction sleeve during introduction of the teat and snugly engages the teat when same is inserted so deep into the suction sleeve that same also snugly fits around the teat. Thus the ring lip forms a kind of a barb which holds the milking cup in its position on the teat during the unloading or massaging cycle because the collapsing or compressing of the suction sleeve causes the teat to be pressed upwardly out of the suction stub. Thus an underpressure which constantly acts onto the teat is not needed in order to hold the milking cup onto the teat. However, at the same time a lever arm is formed through the construction of the ring lip and the suction sleeve which engages at a spaced location from the base of the ring lip said ring lip, practically between the base of the ring lip and the point of engagement of the suction sleeve, against which lever arm the ring lip is pulled by the elastic suction sleeve in the suction cycle in direction of the tapering end of the suction stub. The opening of the ring lip widens so that it does not exert any pressure onto the teat during the suction cycle. Thus the milk flow in the teat is unhindered in the suction cycle.
During the change from the suction cycle to the unloading cycle, when the longitudinal pull or pressure exerted onto the suction sleeve becomes less, the ring lip is placed again against the teat and thus prevents a pressing out of the teat and a falling off of the milking cup from the teat. Since now for holding the milking cup on the teat a vacuum is no longer needed on the upper end of the rubber teat holder, the rubber teat holder can be constructed as a suction sleeve which from the start snugly encloses the teat. Thus the inner wall of the suction sleeve totally supports the part of the teat which extends into said suction sleeve and the vacuum which is applied on the suction sleeve becomes effective periodically practically only on the teat end. From this results an important protection of the entire teat.
To achieve this advantage, the arrangement may also naturally be such that the upper and greater enlarging end of the suction sleeve transfers directly into the holding edge, and that spaced from said transition there is constructed on the suction sleeve a ring lip which projects from said suction sleeve radially inwardly. Such a construction is to be considered as entirely equivalent.
The holding edge is advantageously constructed in form of a bead. This assures a fixed seat and a fixed mounting of the rubber teat holder on the milking cup housing provided for this purpose, without that effecting through this the mode of operation of the rubber teat holder. At the same time it is possible to produce the rubber teat holder in one piece and no special precautionary measures need to be taken for a fixed seat.
It has been proven as being advantageous to construct the bead in such a manner that a part of the bead lies protective above the free edge of the milking cup housing. From this results the effect that when the milking cup strikes the upper edge of the milking cup housing the part of the bead which lies above the edge resiliently absorbs the impact so that the ring lip which starts out from the bead is not struck. This assures a substantially higher operating protection.
The rubber teat holder is advantageously constructed such that the ring lip transfers into the holding edge at a point which is offset radially outwardly with reference to the longitudinal axis of the suction sleeve with respect to the inner edge of the milking cup housing which is to be gripped over by the holding edge. Through this it is possible to keep the distance between the outside of the suction stub and the inner wall of the milking cup housing particularly small so that the pump output, with which the milking cup must be operated, can also be held low.
Furthermore the milking cup remains handy in spite of the inventive advantages due to its small circumference. Furthermore it has proven to be advantageous in reality, to construct the holding edge such that it extends from the point of its transition into the ring lip on its inner side facing the suction stub in a surface which is sloped toward the tapering end of the suction stub. Such a construction serves the general thought to provide between the inside of the ring lip and the holding edge or the inside wall of a milking cup housing connected to the holding edge a free space which permits during the introduction of a teat into the suction stub the inward bending and/or a widening of the opening of the ring lip.
In order to achieve during the suction cycle an enlargement of the opening of the ring lip which is as extensive as possible, additional, radially extending ribs are provided on the ring lip. Several of such ribs may be provided, which are arranged advantageously regularly over the periphery of the ring lip. As particularly advantageous was found an arrangement, in which the reinforcing ribs are arranged each in pairs diametrically opposite one another. Furthermore it has been found to be advantageous in reality to develop the reinforcing ribs with a cross section which changes in its longitudinal direction such that the reinforcing ribs have a maximum reinforcement at the level of the point at which the stronger enlarging end of the suction stub transfers into the ring lip.
In particular the ring lip but also the slightly conically extending part of the suction sleeve are made preferably of a soft, elastic molding material. As such a molding material, for example a silicone rubber, has proven to be very good.